Chaperone Activity of ERD10 and ERD14, Two Disordered Stress-Related Plant Proteins

Abstract

ERD10 and ERD14 (for early response to dehydration) proteins are members of the dehydrin family that accumulate in response to abiotic environmental stresses, such as high salinity, drought, and low temperature, in Arabidopsis (Arabidopsis thaliana). Whereas these proteins protect cells against the consequences of dehydration, the exact mode(s) of their action remains poorly understood. Here, detailed evidence is provided that ERD10 and ERD14 belong to the family of intrinsically disordered proteins, and it is shown in various assays that they act as chaperones in vitro. ERD10 and ERD14 are able to prevent the heat-induced aggregation and/or inactivation of various substrates, such as lysozyme, alcohol dehydrogenase, firefly luciferase, and citrate synthase. It is also demonstrated that ERD10 and ERD14 bind to acidic phospholipid vesicles without significantly affecting membrane fluidity. Membrane binding is strongly influenced by ionic strength. Our results show that these intrinsically disordered proteins have chaperone activity of rather wide substrate specificity and that they interact with phospholipid vesicles through electrostatic forces. We suggest that these findings provide the rationale for the mechanism of how these proteins avert the adverse effects of dehydration stresses.

Tunable Membrane Binding of the Intrinsically Disordered Dehydrin Lti30, a Cold-Induced Plant Stress Protein

“…Consistently, the Lti30 (K 6 ) dehydrin analyzed in this study was found to localize preferentially at membrane surfaces in electron micrographs (Danyluk et al, 1998;Puhakainen et al, 2004). Moreover, dehydrins such as Lti29 (SK 2 ), Erd14 (SK 2 ) (Kovacs et al, 2008), and DHN1 from maize (YSK 2 ) (Koag et al, 2003(Koag et al, , 2009) were found to coelute with lipid vesicles in vitro. When the K-segments of DHN1 were removed by mutation, the truncated versions of the protein displayed reduced ability to associate with the lipid vesicles (Koag et al, 2009).…”

“…Disordered proteins are on the whole found to be degraded ;100 times faster than folded proteins Kovacs et al, 2008;Rantalainen et al, 2009). Interestingly, our data show that binding of Lti30 to LUVs does not protect against degradation (Figure 9).…”

“…Favoring membrane binding, some dehydrins are found to colocalize with membrane surfaces in stressed plant cells (Danyluk et al, 1998;Puhakainen et al, 2004). Moreover, the maize (Zea mays) dehydrin DHN1 (YSK 2 ; see Figure 1 for nomenclature) and the two Arabidopsis thaliana dehydrins, Lti29 and Erd14, are also found to interact with liposomes in vitro (Koag et al, 2003;Kovacs et al, 2008;Koag et al, 2009). Even so, yet other dehydrins (e.g., the soybean [Glycine max] DHN1 [Y 2 K]; Soulages et al, 2003) are not observed to bind lipid vesicles under corresponding conditions.…”

Improved tolerance to salt and water stress in Drosophila melanogaster cells conferred by late embryogenesis abundant protein

“…In this context, a number of reports document that LEA proteins from animal species can prevent aggregation of target proteins in vivo in the complete absence of water stress. An animal group 3 LEA protein from A. avenea (AavLEA1) reduced protein aggregation when co-expressed with self-aggregating polyglutamin proteins or amyloid β-peptide (Chakrabortee et al, 2012;Liu et al, 2011) and chaperone activity was demonstrated for group 2 LEA proteins from A. thaliana (Kovacs et al, 2008). Apparently, some LEA proteins provide cellular protection to plants and animals during water stress despite being mostly intrinsically disordered at these high water contents.…”

The K-Segment of Maize DHN1 Mediates Binding to Anionic Phospholipid Vesicles and Concomitant Structural Changes

“…Because of high hydrophilicity, high content of Gly (.20%), and the lack of a defined threedimensional structure in the pure form (Lisse et al, 1996), DHNs have been categorized as "intrinsically disordered/unstructured proteins" or "hydrophilins" (Wright and Dyson, 1999;Garay-Arroyo et al, 2000;Tompa, 2005;Kovacs et al, 2008). On the basis of compositional and biophysical properties and their link to abiotic stresses, several functions of DHNs have been proposed, including ion sequestration (Roberts et al, 1993), water retention (McCubbin et al, 1985), and stabilization of membranes or proteins (Close, 1996(Close, , 1997.…”